1. Technical Field
The invention includes embodiments that relate to an electrolyte separator structure such as that used for an energy storage device. The invention includes embodiments that relate to a graded integral structure for use as an electrolyte separator structure in an energy storage device. The invention includes embodiments that relate to a method of making the electrolyte separator structure for an energy storage device.
2. Discussion of Related Art
Development work has been undertaken on high temperature rechargeable batteries using sodium for the negative electrode. The liquid sodium negative electrode is separated from a positive electrode by a sodium-ion-conducting solid electrolyte. Suitable material includes beta-alumina and beta″-alumina, known together as beta-alumina solid electrolyte (BASE), which is used as the separator of electrodes. Some electrochemical cells have a metallic casing. The ceramic parts of the cell can be joined or bonded via a sealing material. The sealing material may include a glassy material having undesirable characteristics associated with its use. Bonded ceramic parts formed from dissimilar materials in a high temperature cell may crack due to thermal stress caused by mismatch in the coefficient of thermal expansion. The coefficient of thermal expansion for two ceramic parts can be substantially dissimilar. The sealing material may have a limited life, and bond failure or degradation may cause cell failure due to a direct conduction path between the cathode and anode electrodes.
It may be desirable to have a graded integral structure for use as electrolyte separator structure in an energy storage device that removes the need for sealing materials that are currently necessary. It may be desirable to have a seal structure that differs from those seal structures that are currently available. It may be desirable to have a method of sealing an energy storage device that differs from those methods that are currently available.